1. Field of the Invention
The present invention relates to a driving circuit of a display device, and more particularly, to a driving circuit of an organic electroluminescence (EL) device using a DC-DC converter.
2. Background of the Related Art
Recently, a flat display market is rapidly developing.
A flat display, developed beginning with liquid crystal displays (LCD), has received much attention. A cathode ray tube (CRT), which had been generally used in the field of display for several decades, is recently being replaced with flat displays such as Plasma Display Panel (PDP), Visual Fluorescent Display (VFD), Field Emission Display (FED), Light Emitting Diode (LED), and Electro-luminescence (EL).
With development or the flat display, many studies for decreasing a size of Integrated Circuits (IC) used in the flat display and decreasing the number of external parts are in progress.
A power supply is separately formed outside the ICs without being formed inside the ICs for some reasons. Since ICs for power supply, sold in the market, are separately used, several limitations according to miniaturization and low cost occur.
FIG. 1 is a block diagram illustrating a structure of a related art driving circuit for an organic EL device.
As shown in FIG. 1, the related art driving circuit is divided into an internal circuit portion and an external circuit portion.
Referring to FIG. 1, the external circuit portion includes a power supply 10, a power peripheral unit 20, and an external micro control unit (MCU) 90. The power supply 10 supplies the required power to all parts of the organic EL device. The power peripheral unit 20 consists of an inductor, a diode, and a resistor.
Meanwhile, the internal circuit portion includes an interface unit 50 interfacing display information from the MCU 90, a memory 60 storing the display information transmitted through the interface unit 50, a data processor 30 outputting a display data to a display panel 60 using the display information stored in the memory 60 and a direct current (DC) voltage provided from the power supply 10, a scan processor 40 outputting a scan data to the display panel 80, and a timing control unit 70 controlling a whole timing required for the display.
The related art control unit includes most components inside an IC, however, a power portion, i.e., the power supply 10 and the power peripheral unit 20 are provided outside the IC.
As has been explained, the related art driving circuit for an organic EL device should control the DC voltage supplied to the display panel considering several factors such as external voltage fluctuation.
At this time, additional devices or parts are required outside the IC to properly control the DC voltage.
Also, since the power portion is provided outside the IC, hardware required to connect internal components of the IC with the external power portion is additionally required. For this reason, a volume of the organic EL display device increases, thereby causing difficulty in using the driving circuit.